BEHAVIOR OF CHEMICALLY ACTIVE ORGANIC IMPURITIES IN SODIUM CIRCUITS

Mineral oils and some other organic substances are employed as cooling-agents and lubricators of reactor equipment with movable parts. At normal operation condition these substances are able to penetrate into reactor protective gas plenum in vapor and aerosols forms. Due to their thermolysis and interaction with sodium there are produced hydrogen and different hydrocarbons species, that are detected usually in cover gas. Kinetic of the above processes is dependent on temperature conditions and with temperature increase from 350 to 500 °C the evolution of some hydrocarbons could rise up to 1-2 orders of magnitude. There were published notes on accidental ingress of oil in the primary circuit of fast reactor sodium coolant. Investigation results of such accidents simulation on the experimental sodium circuit are presented in the report. There are discussed results on kinetic of volatile hydrocarbons evolution from oil-pyrolysis products depositions on the circuit pipes walls and gas plenum surfaces. As well, different brands of oil are compared on their behavior in sodium environment.